Gas turbines are widely used in industrial and power generation operations. A typical gas turbine may include a compressor section, a combustion section disposed downstream from the compressor section, and a turbine section disposed downstream from the combustion section. A working fluid such as ambient air flows into the compressor section where it is progressively compressed before flowing into the combustion section. The compressed working fluid is mixed with a fuel and burned within one or more combustors of the combustion section to generate combustion gases having a high temperature, pressure, and velocity. The combustion gases flow from the combustors and expand through the turbine section to produce thrust and/or to rotate a shaft, thus producing work.
The combustors may be annularly arranged between the compressor section and the turbine section. In a particular combustor design, the combustors include one or more axially extending bundled tube fuel injectors that extend downstream from an end cover.
The bundled tube fuel injector generally includes a plurality of pre-mix tubes arranged radially and circumferentially across the bundled tube fuel injector. The pre-mix tubes extend generally parallel to one another. An outer shroud extends circumferentially around the pre-mix tubes downstream from a fuel distribution module of the bundled tube fuel injector. An aft plate extends radially and circumferentially across a downstream end of the outer shroud adjacent to a combustion chamber or zone defined within the combustor. A cooling air or purge air plenum is at least partially defined within the outer shroud between the fuel distribution manifold and the aft plate. In a conventional bundled tube fuel injector, a downstream or end portion of each pre-mix tube extends through the aft plate such that an outlet of each tube is downstream from a hot side surface of the aft plate, thus providing for fluid communication into the combustion chamber or zone.
Each of the pre-mix tubes extends generally axially through the fuel distribution module and the cooling air plenum. The compressed working fluid is routed through inlets of each of the parallel pre-mix tubes upstream from the fuel distribution module. Fuel is supplied to the fuel plenum through the fluid conduit and the fuel is injected into the pre-mix tubes through one or more fuel ports defined within each of the pre-mix tubes. The fuel and compressed working fluid mix inside the pre-mix tubes before flowing out of the outlet which is defined at the downstream or end portion of each of the pre-mix tubes and into the combustion chamber or zone for combustion.
In current bundled tube fuel injector designs, the outer shroud is welded to the fuel distribution module which adds to assembly time and costs. In addition, the outer shroud and/or the weld joint must be cut through via machining or other cutting method and removed from the bundled tube fuel injector to expose the pre-mix tubes for inspection, repair or replacement. However, the cutting process may result in irreparable damage to the outer shroud and/or may require multiple costly and time consuming machining steps such as polishing, grinding and welding in order to prep and reassemble the bundled tube fuel injector. Therefore, an improved bundled tube fuel injector that does not require welding of the outer shroud to the fuel distribution module and/or cutting of the outer shroud to expose the pre-mix tubes would be useful.